1. Field of Invention
The present invention relates to a vehicle interior member having an air bag door portion, and more particularly to a door portion of an air bag system formed in the vehicle interior member, such as an instrument panel. The present invention further relates to a method for molding the same.
2. Description of the Related Art
Conventionally a vehicle interior member having an air bag door portion such as the instrument panel is known and disclosed, for example, in Japanese Patent Application Laid-open No. HEI 9-156443.
In this instrument panel having the air bag door portion, a three-layer skin including a foam layer as an intermediate layer is disposed on a surface (design face) of a resin substrate constituting a body portion and the air bag door portion of the instrument panel.
However, in order to mold the product having the air bag door portion of the instrument panel invisible (designed to have a relief such as a tear line invisible), the following process is required. A three-layer skin 72 having a cut portion 70 for a tear line at a skin side formed on a back surface thereof is set in an upper mold 74 of molds 74 and 76. Then, a resin 78 is injected into the mold as shown in FIG. 9. In this case, when the resin 78 moves along an injection direction (a direction shown by the arrow X in FIG. 9), a foam layer 72A of the three-layer skin 72 is compressed by the resin 78 toward the upper mold 74 (a direction shown by the arrow Y in FIG. 9). As a result, each thickness of two sections of the three-layer skin 72 separated by the cut portion 70 becomes different. Thus, the resin 78 in a molten state flows through the cut portion 70 into the foam layer 72A that is not compressed. As a result, the foam layer 72A is damaged to form, for example, an undesirable recess on the design face of the product, which degrades the quality of the appearance. For this reason, the conventional technology has never achieved an air bag door portion that is invisible.
In view of these problems, it is an object of the invention to provide a vehicle interior member having an air bag door portion that prevents a foam layer from being melted and damaged, has an invisible air bag door portion, and improves design even after setting a three-layer skin formed with a cut portion forming a skin side tear line in a mold and injection insert molding a substrate.
To achieve the above and other objects, according to a first aspect of the present invention, there is provided a vehicle interior member having an air bag door portion including a three-layer skin, a body portion substrate formed of a hard resin material and injection molded together with the three-layer skin, and an air bag door portion substrate formed of the same hard resin material as the body portion and injection molded integrally with the body portion substrate. The air bag door portion substrate has a groove portion forming a substrate side tear line that is formed during the injection molding to define a shape of a projecting portion formed on a mold and torn upon deployment of an air bag. The three-layer skin has a diagonal cut portion forming a skin side tear line that is formed to extend from a face of the three-layer skin, the face being close to the air bag door portion substrate, at a predetermined inclination angle such that an opening portion of the diagonal cut portion is directed substantially toward the groove portion forming the substrate side tear line.
Therefore, if the three-layer skin is set in the mold and then the three-layer skin and the substrate of the body portion and the air bag door portion are integrally molded by injection molding, a resin flow from a cutting direction of the diagonal cut portion is suppressed by a projecting portion formed on the mold to form the groove portion forming the tear line at the substrate side. Accordingly, the resin flows in a reverse direction to the cutting direction of the diagonal cut portion at the opening portion of the diagonal cut portion of the three-layer skin. As a result, even if the three-layer skin is compressed by the resin, each section separated by the diagonal cut portion may not become a different thickness. Also, the resin flow into a foam layer of the three-layer skin through the opening of the diagonal cut portion can be suppressed, thus preventing the foam layer from being melted and damaged. Therefore, the air bag door portion can be made invisible and the design can be improved. Also, the present invention can be easily achieved by adjusting the incline angle of the diagonal cut portion of the three-layer skin and a thickness of the substrate at the groove portion forming the tear line at the substrate side.
According to a second aspect of the present invention, there is provided a vehicle interior member having an air bag door portion including an air bag door portion having a three-layer skin and a substrate formed of a hard resin and injection molded together with the three-layer skin, and a body portion to which the air bag door portion is fixed. The air bag door portion substrate has a groove portion forming a substrate side tear line that is formed during the injection molding to define a shape of a projecting portion formed on a mold and is torn upon deployment of an air. The three-layer skin has a diagonal cut portion forming a skin side tear line which is formed to extend from a face of the three-layer skin, the face being close to the air bag door portion substrate, at a predetermined inclination angle such that an opening portion of the diagonal cut portion is directed toward the groove portion forming the substrate side tear line.
Therefore, in addition to substantially the same advantages as achieved by the first aspect of the invention, the second aspect of the invention achieves the following advantages. Materials for the skins and substrates of the air bag door portion and the body portion can be separately and freely selected. Considering the design face, the skin of the air bag door portion skin and the skin of the air bag door portion may be formed from the same material in order to make the air bag door portion inconspicuous. The substrate of the air bag door portion and the substrate of the body portion substrate may be formed from different kinds of hard resins in accordance with their performance requirements.
According to a third aspect of the present invention, there is provided a vehicle interior member based on the first or second aspect, in which the diagonal cut portion and the groove portion are positioned such that an edge of the substrate of a passenger side portion which has been torn and deployed upon deployment of the air bag door is hidden by the skin.
Therefore, the edge of the substrate of a passenger side portion which has been torn and deployed upon deployment of the air bag door is hidden by an end portion of the skin of the passenger side door portion that has been torn and deployed upon deployment of the air bag door so that the edge is not exposed.
According to a fourth aspect of the invention, there is provided a vehicle interior member having an air bag door portion including a three-layer skin, a body portion substrate formed of a hard resin material and injection molded together with the three-layer skin, and an air bag door portion substrate formed of the same hard resin material as the body portion substrate and injection molded integrally therewith. The three-layer skin has a diagonal cut portion forming a skin side tear line that has a cutting direction inclined in a direction substantially reverse to a flow direction of the hard resin during injection molding of the body portion substrate and the air bag door portion substrate and is torn upon deployment of an air bag.
According to a fifth aspect of the invention, there is provided a vehicle interior member based on the fourth aspect of the invention, wherein the skin side tear line and a substrate side tear line extend in a direction substantially parallel to the flow direction of the hard resin, and wherein the air bag door portion substrate has a thin portion that is formed adjacent to the groove, the thin portion being positioned at a site facing an opening portion of the diagonal cut portion and extending along the opening portion of the diagonal cut portion in a direction substantially parallel to the flow direction of the hard resin.
Therefore, as the thin portion formed in the substrate substantially prevents the resin from flowing toward the opening portion of the diagonal cut portion, the direction of the resin flowing at the opening portion of the diagonal cut portion is in the reverse direction to the cutting direction of the diagonal cut portion. As a result, the resin flow into the foam layer of the three-layer skin through the opening portion of the diagonal cut portion can be suppressed, thus effectively preventing the foam layer from being melted and damaged.
According to a sixth aspect of the invention, there is provided a vehicle interior member having an air bag door portion including an air bag door portion having a three-layer skin and a substrate formed of a hard resin and injection molded together with the three-layer skin, and a body portion to which the air bag door portion is fixed, wherein the three-layer skin has a diagonal cut portion forming a skin side tear line that has a cutting direction inclined in a direction substantially reverse to a flow direction of the hard resin during injection molding of the air bag door portion substrate and is torn upon deployment of an air bag.
According to a seventh aspect of the present invention, there is provided a method for molding a vehicle interior member having an air bag door portion including the steps of: setting a three-layer skin having a diagonal cut portion with a cutting direction inclined relative to a surface in a first mold; assembling the first mold and a second mold; injecting a hard resin into a cavity defined by the three-layer skin and the second mold to form a substrate of an interior member integrally with the three-layer skin while controlling injection of the hard resin such that a flow direction of the hard resin is substantially opposite to the cutting direction of the diagonal cut portion; and cooling an integral molding of the three-layer skin and the substrate after injecting the hard resin.